Refer to this thread, blizzard closed it blaming players, but people were still consistently having issues at the time they closed it, 327 comments there:
For me, in Italy, the lag started again today just before 20, which is basically peak time, these kind of issues seem to happen more often when there’s more people online.
A free VPN can only solve the issue inconsistently, in my first session it reduced the lag to 100 ms, in the second it’s ineffective.